glTF file import creates files that are too large

[gelvinp]

Godot version

4.0 noticed since beta 4

System information

Windows 10 and Arch Linux

Issue description

When importing a glb or gltf file, the .scn file created in .godot/imported is much much larger than creating a new inherited scene, clearing inheritance (so the scene contains all the mesh information), and saving that as a .scn manually.

I've noticed this in my own projects, where manually creating a .scn file by clearing inheritance results in a file that is 60 KB, whereas the .scn file created by godot in the .godot/imported folder is 3.1 MB, 50 times larger. In this same project, adding together the file sizes of all the .scn files created by importing either a .glb or .gltf file shows that there are 700 MB of .scn files. The entire size of my assets folder including textures and audio is only 192 MB. By manually turning every glb or gltf file into a .scn by clearing inheritance, and then excluding *.glb and *.gltf resources in my export profile, I can bring my pck down from 767 MB to 73 MB, a 10 times reduction in size.

Steps to reproduce

1. Open blender, and export a default cube as a gltf or glb into a Godot project.

2. Open Godot, importing the model. Navigate to .godot/imported and notice the size of the created .scn file.
   

3. Right click on the gltf file in Godot, choose "New inherited scene". Save this scene as a .scn file. Then, right click on the root node and select "Clear inheritance", and save again. Notice the size of this .scn file.
   
   In this example, the file I created is 2.6 times smaller.

4. Go to the scene menu, and choose "Save Scene As", saving it as a .tscn file. Notice the size of the file.
   
   The .tscn file is smaller than the .scn file created by Godot, even though it is text based and not binary and thus should be larger.

5. Navigate to the .godot/imported directory and copy the created .scn file into your Godot project. Open the .scn file in the editor, and as in step 4, save it as a .tscn file as well. Note the file size.
   
   Notice that now, it is the same size as the .tscn file I created in step 4.

6. Diff these two .tscn files together.
   
   Notice that the only difference between the file created manually by making a new scene and clearing inheritance, and the file created automatically by Godot on import, is the uid assigned to the scene. Therefore, there has been zero loss of content or functionality to explain why the .scn created manually is 2.6 times smaller.

7. Reopen the .scn file created automatically by Godot during import, and "Save Scene As" again, but this time, continue to save it as a .scn file, just with a new name. Note the file size.
   
   Even though no modifications were made to the file, and it was simply resaved into the same file format, it is still 2.6 times smaller than the file created automatically by Godot.

Minimal reproduction project

gltf.zip

[gelvinp]

As an aside, opening up the automatically generated .scn file in a text editor shows that, unlike scenes manually saved as a .scn file, the imported scene is largely text:

[lyuma]

Is this still an issue in 4.0 rc2?

We now extract textures by default in glb files.
If textures are extracted, does this issue no longer happen?

[gelvinp]

Is this still an issue in 4.0 rc2?

We now extract textures by default in glb files. If textures are extracted, does this issue no longer happen?

I would assume so, but I will check right now (EDIT: Yes, it is still the case.)

In the steps that I outlined in my issue, there were no textures to extract. The difference likely comes down to the file format used. The automatically imported scenes start with a "RSRC" header, and have the ascii string "PackedScene" near the top of the file, while the manually saved scenes start with a "RSCC" header (compressed?), and have no apparent ascii strings.

[gelvinp]

(Ignore the closed issue, clicked the wrong button)

[Calinou]

I can confirm this on 4.1.dev 33957ae (Linux).